CHAPTER V 



A STUDY OF STIMULANTS, NARCOTICS, AND POISONS 



1. DEFINITION OF STIMULANT, NARCOTIC, AND POISON 



Definition of a Stimulant. In the preceding chapter we 

 have discussed those substances that yield material for the 

 repair or growth of the body, or that supply the fuel used 

 by the body in producing heat or power to do work. But 

 in addition to the various nutrients that can be used for one 

 or all of these purposes, we often take with our foods cer- 

 tain substances that are not used in any of these ways. For 

 example, pepper, mustard, vinegar, tea, and coffee never be- 

 come a part of our living substance, nor are they consumed 

 in any considerable amount to supply us with energy. 

 Hence, we cannot regard these compounds as foods. Most 

 of them, however, add an agreeable flavor to our foods, and 

 so stimulate our appetites and aid in the digestion of the 

 real nutrients. 



Most of these compounds, also, do no harm in our bodies 

 if taken in moderate quantities, and so we cannot regard 

 them as poisons ; for the Century Dictionary defines a poi- 

 son as " any substance which, introduced into the living organ- 

 ism directly, tends to destroy the life or impair the health of 

 that organism" 



We are considering, then, a class of substances that are 

 neither foods in a strict sense, nor are they poisons. This 

 sort of compounds we call stimulants. A stimulant is any 

 agent that temporarily quickens some process in the body. 

 When we wish to quicken the activities of a horse, we touch 

 him more or less with a whip, which acts like a stimulant. 



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